Multimeters are used to measure a variety of electrical parameters such as AC voltage, AC current, DC voltage, DC current, and resistance. Clamp meters are a type of multimeters with a current sensing clamp.
Clamp meters are designed to measure current without breaking the current path and typically have two clamp jaws which open and close at a fixed position with respect to the body and display of the clamp meter. Current is measured by opening the jaws to close them around the conductor element carrying the current. The clamps are provided with electrical coils inside them. In the closed position of the clamp jaws, the current flowing in the conductor element (such as a busbar or a cable), of an electrical circuit magnetically induces current in the coils. This current is proportional to the current flowing through the conductor element. For measuring the electrical current, there does not need to be a electrical contact between the conductor element and the clamps.
The conventional clamp meters have a rectangular housing designed to be held in one hand. A pair of clamp jaws extends from one end of the housing. A trigger is provided to operate the opening and closing of the clamps in order to access the conductor whose measurement is to be taken. In conventional clamp meters, the clamp jaws can be opened and closed with a thumb operated lever which is present just below one of the two clamp jaws that are present in these clamp meters. The opening of clamp jaws may require substantial force. This can cause fatigue to the hand of the operator as all the force required to open the clamp jaws for enclosing the conductor is sustained by the thumb.
A drawback of the existing clamp meters is they are awkward to use in many circumstances. For example, there are many situations where the conductor elements that need monitoring are tightly and awkwardly placed in congested physical configurations, or placed in an overhead location, thereby making it awkward to work with them. Under these circumstances, when the clamp jaws are placed around conductor, the display and the keys might be orientated into a position which makes reading the display and operation of the clamp meter very difficult if not impossible.
The operator of the clamp meter tries, under such circumstances, either to take a reading by putting at risk their personal safety or they may not take any measurements at all on the grounds of lack of safe access to the conductor element.
As a further drawback of the existing clamp meters, as the thumb-operated lever is very close to the clamps, user is exposed to dangerously high voltage when measuring the current in the live and often bare conductor elements. When accessing conductors situated in congested or awkward locations, there is also a possibility that the clamp may slip accidentally and user may touch the live conductor and get electrocuted and thus could suffer serious injuries or fatality. This poses a definite risk to the property which houses the electric panels that contain such electric conductor elements.
There is therefore a need to provide a mechanism by which it will be possible for the operator to operate a clamp meter with the use of less hand movement than required by the existing clamp meters, thereby enabling them to operate the clamp meter with greater safety than in case of the existing clamp meters. There is also a need to provide a clamp meter that can be operated with lesser force than required for the existing clamp meters, thereby reducing the fatigue that the operator experiences under such working conditions.
Clamp meter with safe trigger mechanism invention relates to measurement of current in the live bare conductor with trigger mechanism at the bottom side and away from the clamps to reduce the possibility of electric shock and operation of the trigger with more than one finger for reducing the fatigue to the operator.